Integrated photocatalytic advanced oxidation system (TiO2/UV/O3/H2O2) for degradation of volatile organic compounds

Photo-transformation of ofloxacin in natural aquatic conditions: Impact of indirect photolysis on the product profile and transformation mechanism

The natural phototransformation of organic pollutants in the environment depends on several water constituents, including inorganic ions, humic substances, and pH. However, the literature information concerning the influence of various water components on the amount of phototransformation and their impact on the development of various transformation products (TPs) is minimal. This study investigated the phototransformation of ofloxacin (OFL), a fluoroquinolone antibiotic, in the presence of various water components such as cations (K+, Na+, Ca2+, NH4+, Mg2+), anions (NO3-, SO42-, HCO3-, CO32-, PO43-), pH, and humic substances when exposed to natural sunlight. The study reveals that neutral pH levels (0.39374 min⁻1) enhance the phototransformation of OFL in aquatic environments. Carbonate, among anions, shows the highest rate constant (2.89966 min⁻1), significantly influencing OFL phototransformation, while all anions exhibit a notable impact. In aquatic environments, indirect phototransformation of OFL, driven by increased reactive oxygen species, expedites light-induced reactions, potentially enhancing OFL phototransformation. A clear difference was visible in the type of transformation products (TPs) formed during direct and indirect photolysis. The impact of indirect photolysis in the product profile was evaluated by examining the unique properties of TPs in direct and indirect photolysis. The primary transformation products were generated by oxidation and cleavage processes directed towards the ofloxacin piperazinyl, oxazine, and carboxyl groups. The toxicity assessment of TPs derived from OFL revealed that among the 26 identified TPs, TP3 (demethylated product), TP7 and TP8 (decarboxylated products), and TP15 (piperazine ring cleaved product) could potentially have some toxicological effects. These findings suggest that the phototransformation of OFL in the presence of various water components is necessary when assessing this antibiotic's environmental fate.

A comprehensive review and perspective research in technology integration for the treatment of gaseous volatile organic compounds

Volatile organic compounds (VOCs) are harmful pollutants emitted from industrial processes. They pose a risk to human health and ecosystems, even at low concentrations. Controlling VOCs is crucial for good air quality. This review aims to provide a comprehensive understanding of the various methods used for controlling VOC abatement. The advancement of mono-functional treatment techniques, including recovery such as absorption, adsorption, condensation, and membrane separation, and destruction-based methods such as natural degradation methods, advanced oxidation processes, and reduction methods were discussed. Among these methods, advanced oxidation processes are considered the most effective for removing toxic VOCs, despite some drawbacks such as costly chemicals, rigorous reaction conditions, and the formation of secondary chemicals. Standalone technologies are generally not sufficient and do not perform satisfactorily for the removal of hazardous air pollutants due to the generation of innocuous end products. However, every integration technique complements superiority and overcomes the challenges of standalone technologies. For instance, by using catalytic oxidation, catalytic ozonation, non-thermal plasma, and photocatalysis pretreatments, the amount of bioaerosols released from the bioreactor can be significantly reduced, leading to effective conversion rates for non-polar compounds, and opening new perspectives towards promising techniques with countless benefits. Interestingly, the three-stage processes have shown efficient decomposition performance for polar VOCs, excellent recoverability for nonpolar VOCs, and promising potential applications in atmospheric purification. Furthermore, the review also reports on the evolution of mathematical and artificial neural network modeling for VOC removal performance. The article critically analyzes the synergistic effects and advantages of integration. The authors hope that this article will be helpful in deciding on the appropriate strategy for controlling interested VOCs.

Mechanism and ecological environmental risk assessment of peroxymonosulfate for the treatment of heavy metals in soil

Oxidation technologies based on peroxymonosulfate (PMS) have been effectively used for the remediation of soil organic pollutants due to their high efficiency. However, the effects of advanced PMS-based oxidation technologies on other soil pollutants, such as heavy metals, remain unknown. In this study, changes in the form of heavy metals in soil after using PMS and the risk of pollution to the ecological environment were investigated. Furthermore, two risk assessment methods, the mung bean germination toxicity test and groundwater leaching soil column test, were employed to evaluate the soil before and after PMS treatment. The results showed that PMS has a strong ability to degrade complex compounds, enabling the transformation of heavy metals, such as Cd, Pb, and Zn, from stable to active states in the soil. The risk assessments showed that PMS treatment activated heavy metals in the soil, which delayed the growth of plants, increased heavy metal content in plant tissues and the risk of groundwater pollution. These findings provide a new perspective for understanding the effects of PMS on soil, thus facilitating the sustained and reliable development of future research in the field of advanced oxidation applied to soil treatment.

A theoretical study on toluene oxidization by OH radical

Toluene, a prominent member of volatile organic compounds (VOCs), exerts a substantial adverse influence on both human life and the environment. In the context of advanced oxidation processes, the ·OH radical emerges as a highly efficient oxidant, pivotal in the elimination of VOCs. This study employs computational quantum chemistry methods (G4MP2//B3LYP/6-311++G(d,p)) to systematically investigate the degradation of toluene by ·OH radicals in an implicit solvent model, and validates the rationale of choosing a single-reference method using T1 diagnostics. Our results suggest three possible reaction mechanisms for the oxidation of toluene by ·OH: firstly, the phenyl ring undergoes a hydrogen abstraction reaction followed by direct combination with ·OH to form cresol; secondly, ·OH directly adds to the phenyl ring, leading to ring opening; thirdly, oxidation of sidechain to benzoic acid followed by further addition and ring opening. The last two oxidation pathways involve the ring opening of toluene via the addition of ·OH, significantly facilitating the process. Therefore, both pathways are considered feasible for the degradation of toluene. Subsequently, the UV-H2O2 system was designed to induce the formation of ·OH for toluene degradation and to identify the optimal reaction conditions. It was demonstrated that ·OH and 1O2 are the primary active species for degrading toluene, with their contribution ranking as ·OH > 1O2. The intermediates in the mixture solution after reactions were characterized using GC-MS, demonstrating the validity of theoretical predictions. A comparative study of the toluene consumption rate revealed an experimental comprehensive activation energy of 10.33 kJ/mol, which is consistent with the preliminary activation energies obtained via theoretical analysis of these three mechanisms (0.56 kJ/mol to 13.66 kJ/mol), indicating that this theoretical method can provide a theoretical basis for experimental studies on the oxidation of toluene by ·OH.

The treatment of petrochemical wastewater via ozone-persulfate coupled catalytic oxidation: mechanism of removal of soluble organic matter

Petrochemical wastewater contains a variety of organic pollutants. Advanced oxidation processes (AOPs) are used for deep petrochemical wastewater treatment with distinct advantages, including the complete mineralization of organic substances, minimal residual byproducts, and compatibility with biological treatment systems. This work evaluates the effectiveness of three methods, namely, ozone, persulfate, and O3-PMS (ozone-persulfate) processes, which were compared to remove soluble organic matter. The O3-PMS process offered significant advantages in terms of organic matter removal efficiency. This process involves ozone dissolution in an aqueous persulfate solution, producing a more significant amount of hydroxyl radicals in comparison to single AOPs. The production of hydroxyl radicals and the synergistic effect of hydroxyl radicals and persulfate radicals were investigated. In the O3-PMS process, transition metal ions were added to understand the mechanism of the O3-PMS coupled catalytic oxidation system. The results showed that when the ozone concentration was in the range of 5 ~ 25 mg/L, the dosage of persulfate was in the range of 0.01 ~ 0.05 mol/L, the dosage of metal compounds was in the range of 0:0 ~ 2:1, and the reaction time was in the range of 0 ~ 2 h; the optimum chemical oxygen demand (CODCr) and total organic content (TOC) removal effect was achieved under the coupled system with an ozone concentration of 10 mg/L, a persulfate dosage of 0.02 mol/L, a 1:2 dosage ratio of between Fe2+ and Cu2+ compounds, and a reaction time of 2 h. Under optimal reaction conditions, the rates of CODCr and TOC removal reached 70% and 79.3%, respectively. Furthermore, the removal kinetics of the O3-PMS coupled catalytic oxidation system was analyzed to optimize the removal conditions of COD and TOC, and the mechanism regulating the degradation of dissolved organic matter was explored by three-dimensional fluorescence and GC-MS technology. Thus, O3-PMS coupled catalytic oxidation is an effective process for the deep treatment of wastewater. The careful selection of transition metal ions serves as a theoretical foundation for the subsequent preparation of catalysts for the ozone persulfate oxidation system, and this study provides a suitable reference for removing organic matter from petrochemical wastewater.

Flexible Antibacterial Respiratory Monitoring Sensor Based on Controllable Au-Modified Surface of Highly {001} Preferred Anatase Titanium Dioxide Thin Film

Respiratory signals are critical clinical diagnostic criteria for respiratory diseases and health conditions, and respiratory sensors play a crucial role in achieving the desired respiratory monitoring effect. High sensitivity to a single factor can improve the reliability of respiratory monitoring, and maintaining the hygiene of the sensors is also important for daily health monitoring. Herein, we propose a flexible Au-modified anatase titanium dioxide resistive respiratory sensor, which can be mechanically compliantly attached to curved surfaces for respiratory monitoring in different modalities (i.e., respiratory intensity, frequency, and rate). The uniform and preferentially oriented anatase titanium dioxide films gained by the polymer-assisted deposition technique can be fabricated on flexible substrates through a liquid-assisted transferring process. The Au modification can enhance surface plasmon resonance to facilitate the photocatalytic activity of titanium dioxide, and the optimized distribution of Au on the surface of titanium dioxide film made the sensor have an excellent antibacterial effect. The uniquely designed encapsulation can effectively control the contact between the surface of titanium dioxide films and electrodes, allowing the flexible sensor to exhibit fast response time (0.71 s) and recovery time (1.06 s) to respiratory as well as insensitivity or low sensitivity to other factors (i.e., gas composition, humidity, temperature, stress, and strain). This work provided an effective strategy for flexible wearable respiratory sensors and has great potential in daily respiratory monitoring for health management and pandemic control.

Preparation of Mn-doped sludge biochar and its catalytic activity to persulfate for phenol removal

In recent years, the increasing prevalence of phenolic pollutants emitted into the environment has posed severe hazards to ecosystems and living organisms. Consequently, there is an urgent need for a green and efficient method to address environmental pollution. This study utilized waste sludge as a precursor and employed a hydrothermal-calcination co-pyrolysis method to prepare manganese (Mn)-doped biochar composite material (Mn@SBC-HP). The material was used to activate peroxydisulfate (PDS) for the removal of phenol. The study investigated various factors (such as the type and amount of doping metal, pyrolysis temperature, catalyst dosage, PDS dosage, pH value, initial phenol concentration, inorganic anions, and salinity) affecting phenol removal and the mechanisms within the Mn@SBC-HP/PDS system. Results indicated that under optimal conditions, the Mn@SBC-HP/PDS system achieved 100% removal of 100 mg/L phenol within 180 min, with a TOC removal efficiency of 82.7%. Additionally, the phenol removal efficiency of the Mn@SBC-HP/PDS system remained above 90% over a wide pH range (3-9). Free radical quenching experiments and electron spin resonance (ESR) results suggested that hydroxyl radicals (·OH) and sulfate radicals (SO4-) yed a role in the removal of phenol through radical pathways, with singlet oxygen (1O2) being the dominant non-radical pathway. The phenol removal efficiency remained above 90%, demonstrating the excellent adaptability of the Mn@SBC-HP/PDS system under the interference of coexisting inorganic anions or increased salinity. This study proposes an innovative method for the resource utilization of waste, creating metal-biochar composite catalysts for the remediation of water environments. It provides a new approach for the efficiency of organic pollutants in water environments.

Singlet oxygen-dominated peroxymonosulfate activation by layered crednerite for organic pollutants degradation in high salinity wastewater

Advanced oxidation processes have been widely studied for organic pollutants treatment in water, but the degradation performance of radical-dominated pathway was severely inhibited by the side reactions between the anions and radicals, especially in high salinity conditions. Here, a singlet oxygen (1O2)-dominated non-radical process was developed for organic pollutants degradation in high salinity wastewater, with layered crednerite (CuMnO2) as catalysts and peroxymonosulfate (PMS) as oxidant. Based on the experiments and density functional theory calculations, 1O2 was the dominating reactive species and the constructed Cu-O-Mn with electron-deficient Mn captured electron from PMS promoting the generation of 1O2. The rapid degradation of bisphenol A (BPA) was achieved by CuMnO2/PMS system, which was 5-fold and 21-fold higher than that in Mn2O3/PMS system and Cu2O/PMS system. The CuMnO2/PMS system shown prominent BPA removal performance under high salinity conditions, prominent PMS utilization efficiency, outstanding total organic carbon removal rate, wide range of applicable pH and good stability. This work unveiled that the 1O2-dominated non-radical process of CuMnO2/PMS system overcame the inhibitory effect of anions in high salinity conditions, which provided a promising technique to remove organic pollutants from high saline wastewater.

Photoelectrochemical advanced oxidation processes for simultaneous removal of antibiotics and heavy metal ions in wastewater using 2D-on-2D WS2@CoFe2O4 heteronanostructures

The presence of antibiotics in water poses significant threats to both human health and the environment. Addressing this issue requires the effective treatment of medical wastewater. Photoelectrochemical advanced oxidation processes (PEAOPs) are emerging as promising solutions for wastewater treatment. This process utilizes photocatalysts to convert charge carriers into reactive species such as hydroxyl radicals and superoxide ions, which are essential for degrading pollutants in wastewater. However, limitations in charge carrier separation and transport have hindered the efficiency of photoelectrochemical advanced oxidation processes. To overcome these limitations, we designed WS2@CoFe2O4 heterojunctions, optimizing their energy levels to enhance charge transport and separation. This improvement significantly increased the oxidation of antibiotics such as amoxicillin and azithromycin. Multiple reactions occurred at the WS2@CoFe2O4 heterojunctions during photoelectrochemical advanced oxidation processes, leading to the impressive degradation of up to 99% of antibiotics under visible light irradiation at 0.8 V. Urea and H2O2 acted as oxidation agents within photoelectrochemical advanced oxidation processes, amplifying the generation of hydroxyl radicals and superoxide ions, further enhancing antibiotic oxidation. Moreover, the WS2@CoFe2O4 photoanode efficiently oxidized toxic antibiotics while converting As(III) into the less harmful As(V). Crucially, recyclability tests confirmed the robustness of the WS2@CoFe2O4 photoanode, ensuring its suitability for prolonged use in photoelectrochemical advanced oxidation processes. Integrating WS2@CoFe2O4 photoanodes into water purification systems can enhance efficiency, reduce energy consumption, and improve economic viability. This technology's scalability and its ability to protect ecosystems while conserving water resources make it a promising solution for addressing the critical issue of antibiotic pollution in water environments.

Degradation of polycyclic aromatic hydrocarbons (PAHs) in smoked sausages by ultraviolet irradiation

BACKGROUND

Ultraviolet (UV) irradiation has been widely employed to disinfect food, however, the efficacy of UV irradiation in degrading polycyclic aromatic hydrocarbons (PAHs) in smoked sausages has not been explored. In this article, the UV degradation ability of PAHs in smoked sausages was investigated with different UV irradiation conditions, including different irradiation powers, durations and wavelengths. The effects of UV radiation on the quality of sausages were also evaluated, and potential degradation mechanisms were elucidated.

RESULTS

The results showed that the irradiation duration was the primary determinant of PAHs degradation, achieving 84.4% and 84.2% degradation rates at 16 W and 32 W power for 30 min, respectively. Among the three UV wavelengths assessed, 254 nm demonstrated a significantly higher degradation rate for benzo[a]pyrene (BaP), PAH4 and PAHs compared to 365 nm and 310 nm. To further explore the degradation mechanism, UV irradiation was combined with water, 0.1 mol/L hydrogen peroxide (H2 O2 ) and 0.1 mol/L ascorbic acid (vitamin C) coatings. The 0.1 mol/L H2 O2 coating exhibited the most pronounced degradation effect, suggesting that the highly reactive oxygen hydroxyl radicals (·OH) generated by UV irradiation played a critical role in initiating redox reactions.

CONCLUSION

This systematic investigation paves the way for developing novel strategies to eliminate PAHs or other organic contaminants from smoked sausages. © 2023 Society of Chemical Industry.

Chalcopyrite as an oxidants activator for organic pollutant remediation: A review of mechanisms, parameters, and future perspectives

Advanced oxidation processes (AOPs) based on oxidants have attracted attention for the degradation of organic pollutants. The combination of chalcopyrite with oxidants such as persulfate, peroxide, percarbonate, and others shows promise as a system due to its ability to activate through various pathways, leading to the formation of numerous radical and non-radical species. In this review, the generation of sulfate radical (SR) and hydroxyl radical (HR) in AOPs were summarized. The significance of chalcopyrite in various approaches including Fenton, photo-Fenton, and photo/Fenton-like methods, as well as its involvement in electrochemical Fenton-based processes was discussed. The stability and reusability, toxicity, catalyst mechanism, and effects of operational parameters (pH, catalyst dosage, and oxidant concentration) are evaluated in detail. The review also discusses the role of Fe2+/3+, Cu1+/2+, S2- and Sn2- present in CuFeS2 in the generation of free radicals. Finally, guidelines for future research are presented in terms of future perspectives.

Determination of lindane in surface water samples and its degradation by hydrogen peroxide and persulfate assisted TiO2-based photocatalysis

Organochlorine pesticides (OCPs) have been used extensively as insecticides and herbicides. This study investigates the occurrence of lindane in surface water from the Peshawar valley (i.e., Peshawar, Charsadda, Nowshera, Mardan and Swabi districts of Khyber Pakhtunkhwa, Pakistan). Out of 75 samples tested (i.e., 15 samples from each district), 13 samples (including 2 from Peshawar, 3 from Charsadda, 4 from Nowshera, 1 from Mardan, and 3 from Swabi) are found to be contaminated with lindane. Overall, the detection frequency is 17.3%. The maximum concentration of lindane is detected in a water sample from Nowshera and found to be 2.60 μg L^-1. Furthermore, the degradation of lindane in the water sample from Nowshera, containing the maximum concentration, is investigated by simulated solar-light/TiO₂ (solar/TiO₂), solar/H₂O₂/TiO₂ and solar/persulfate/TiO₂ photocatalysis. The degradation of lindane by solar/TiO₂ photocatalysis is 25.77% after 10 h of irradiation. The efficiency of the solar/TiO₂ process is significantly increased in the presence of 500 μM H₂O₂ and 500 μM persulfate (PS) (separately), represented by 93.85 and 100.00% lindane removal, respectively. The degradation efficiency of lindane is lower in natural water samples as compared to Milli-Q water, attributed to water matrix effect. Moreover, the identification of degradation products (DPs) shows that lindane follows similar degradation pathways in natural water samples as the one in Milli-Q water. The results show that the occurrence of lindane in surface waters of Peshawar valley is a matter of great concern for human beings and the environment. Interestingly, H₂O₂ and PS assisted solar/TiO₂ photocatalysis is an effective method for the removal of lindane from natural water.

Norfloxacin removal by ultraviolet-activated sodium percarbonate and sodium hypochlorite: process optimization and anion effect

The efficiency of UV-activated sodium percarbonate (SPC) and sodium hypochlorite (SHC) in Norfloxacin (Norf) removal from an aqueous solution was assessed. Control experiments were conducted and the synergistic effect of the UV-SHC and UV-SPC processes were 0.61 and 2.89, respectively. According to the first-order reaction rate constants, the process rates were ranked as UV-SPC > SPC > UV and UV-SHC > SHC > UV. Central composite design was applied to determine the optimum operating conditions for maximum Norf removal. Under optimum conditions (UV-SPC: 1 mg/L initial Norf, 4 mM SPC, pH 3, 50 min; UV-SHC: 1 mg/L initial Norf, 1 mM SHC, pH 7, 8 min), the removal yields for the UV-SPC and UV-SHC were 71.8 and 72.1%, respectively. HCO₃^-, Cl^-, NO₃^-, and SO₄^2- negatively affected both processes. UV-SPC and UV-SHC processes were effective for Norf removal from aqueous solution. Similar removal efficiencies were obtained with both processes; however, this removal efficiency was achieved in a much shorter time and more economically with the UV-SHC process.

Reduction of the environmental impact of wastewater from the pretreatment of biodiesel production: A hybrid proposal for decontamination via photo-electro-Fenton/Fered/O3

Complex wastewater is generated during biodiesel production. We propose a new solution for the treatment of wastewater from enzymatic pretreatment of biodiesel production (WEPBP) by using a hybrid system based on the photo-Fered-Fenton process with O₃ assistance (PEF-Fered-O₃). We applied response surface methodology (RSM) to determine the suitable conditions for the PEF-Fered-O₃ process: a current intensity of 3 A, an initial solution pH controlled at 6.4, an initial H₂O₂ concentration of 12,000 mg L^-1, and an O₃ concentration of 50 mg L^-1. We performed three new experiments under similar conditions with slight changes to the conditions, namely a longer reaction time (120 min) and single or periodic H₂O₂ addition (i.e., small H₂O₂ additions at different reaction times). Periodic H₂O₂ addition provided the best removal results probably by reducing the occurrence of undesired side reactions that cause hydroxyl radical (^•OH) scavenging. With the application of the hybrid system, the chemical oxygen demand (COD) and total organic carbon (TOC) decreased by 91% and 75%, respectively. We also evaluated the presence of metals such as iron, copper, and calcium; electric conductivity; and voltage at 5, 10, 15, 30, 45, 60, 90, and 120 min. We submitted raw and treated WEPBP sludge samples to X-ray diffraction to study the degree of crystallinity. There was a rearrangement of the compounds present in treated WEPBP, possibly caused by oxidation of a large fraction of organic matter. Finally, we evaluated the genotoxicity and cytotoxicity of WEPBP by using Allium cepa meristematic root cells. Treated WEPBP was less toxic to these cells, denoted by improvements in gene regulation and cell morphology. Given the current scenario for the biodiesel industry, applying the proposed hybrid PEF-Fered-O₃ system at suitable conditions provides an efficient alternative to treat a complex matrix, namely WEPBP, to reduce its potential to cause abnormalities in the cells of living organisms. Thus, the negative impacts of the discharge of WEPBP in the environment might be reduced.

Advanced oxidation processes for removal of monocyclic aromatic hydrocarbon from water: Effects of O3/H2O2 and UV/H2O2 treatment on product formation and biological post-treatment

Several oxidative treatment technologies, such as ozonation or Fenton reaction, have been studied and applied to remove monocyclic hydroaromatic carbon from water. Despite decades of application, little seems to be known about formation of transformation products while employing different ozone- or ^∙OH-based treatment methods and their fate in biodegradation. In this study, we demonstrate that O₃/H₂O₂ treatment of benzene, toluene, ethylbenzene (BTE), and benzoic acid (BA) leads to less hydroxylated aromatic transformation products compared to UV/H₂O₂ as reference system - this at a similar ^∙OH exposure and parent compound removal efficiency. Aerobic biodegradation tests after oxidation of 0.15 mM BA (12.6 mg C L^-1 theoretical DOC) revealed that a less biodegradable DOC fraction > 4 mg C L^-1 was formed in both oxidative treatments compared to the BA control. No advantage of ozonation over UV/H₂O₂ treatment was observed in terms of mineralization capabilities, however, we detected less transformation products after oxidation and biodegradation using high-resolution mass spectrometry. Biodegradation of BA that was not oxidized was more complete with minimal organic residual. Overall, the study provides new insights into the oxidation of monocyclic aromatics and raises questions regarding the biodegradability of oxidation products, which is relevant for several treatment applications.

Recent advances in advanced oxidation processes (AOPs) for the treatment of nitro- and alkyl-phenolic compounds

The presence of phenolic compounds in the aquatic environment has posed severe risks due to their toxicity. Among the phenolic families, nitro- and alkyl-phenolic compounds have been categorized as precedence contaminants by the United States Environmental Protection Agency (US EPA). Therefore, efficient treatment methods for wastewater containing nitro- and alkyl-phenolic compounds are urgently needed. Due to the advantages of creating reactive species and generating efficient degradation of hazardous contaminants in wastewater, advanced oxidation processes (AOPs) are well-known in the field of treating toxic contaminants. In this review paper, the recent directions in AOPs, catalysts, mechanisms, and kinetics of AOPs are comprehensively reviewed. Furthermore, the conclusion summarizes the research findings, future prospects, and opportunities for this study. The main direction of AOPs lies on the optimization of catalyst and operating parameters, with industrial applications remain as the main challenge. This review article is expected to present a summary and in-depth understanding of AOPs development; and thus, inspiring scientists to accelerate the evolution of AOPs in industrial applications.

Efficacy of simultaneous advanced oxidation and adsorption for treating municipal wastewater for indirect potable reuse

The main scope of this study was to compare the efficacy of different advanced oxidation processes (AOPs) combined with adsorption for treating secondary treated effluent of municipal wastewater in a continuous-lab-scale reactor. The results revealed enhanced removal of biological oxygen demand (BOD: C₀: 14.1 and C_t: 0 mg L^-1 (100%)), chemical oxygen demand (COD: C₀: 40.5 and C_t: 4 mg L^-1 (≤90%)), and total organic carbon (TOC: C₀: 15.2 and C_t: 3.02-3.63 mg L^-1 (∼80%)) by UV/PMS, O₃/PMS, UV/O₃/H₂O₂, and UV/O₃/MnO₂ processes followed by glass packed bed reactor (GPBR). Complete inactivation of the bacterial count was observed for all the studied processes. The GPBR showed the additional advantage of termination in the regrowth of bacterial count on the filtering medium. The gas-chromatography and mass spectrometry (GC-MS) analysis showed that AOP followed by adsorption reduced the concentrations of the by-products in the treated effluent. Overall, the synergy between AOP and adsorption improved the effluent quality to meet various indirect potable reuse (IPR) applications.

Remediation of phthalate acid esters from contaminated environment—Insights on the bioremedial approaches and future perspectives

Phthalates are well-known emerging pollutants that are toxic to the environment and human health. Phthalates are lipophilic chemicals used as plasticizers in many of the items for improving their material properties. These compounds are not chemically bound and are released to the surroundings directly. Phthalate acid esters (PAEs) are endocrine disruptors and can interfere with hormones, which can cause issues with development and reproduction, thus there is a huge concern over their existence in various ecological surroundings. The purpose of this review is to explore the occurrence, fate, and concentration of phthalates in various environmental matrices. This article also covers the phthalate degradation process, mechanism, and outcomes. Besides the conventional treatment technology, the paper also aims at the recent advancements in various physical, chemical, and biological approaches developed for phthalate degradation. In this paper, a special focus has been given on the diverse microbial entities and their bioremedial mechanisms executes the PAEs removal. Critically, the analyses method for determining intermediate products generated during phthalate biotransformation have been discussed. Concluisvely, the challenges, limitations, knowledge gaps and future opportunities of bioremediation and their significant role in ecology have also been highlighted.

Advanced oxidation process: a sustainable technology for treating refractory organic compounds present in industrial wastewater

The world faces tremendous challenges and environmental crises due to the rising strength of wastewater. The conventional technologies fail to achieve the quality water that can be reused after treatment means "zero effluent" discharge of the industrial effluent. Therefore, now the key challenge is to develop improved technologies which will have no contribution to secondary pollution and at the same time more efficient for the socio-economic growth of the environment. Sustainable technologies are needed for wastewater treatment, reducing footprint by recycling, reusing, and recovering resources. Advanced oxidation process (AOP) is one of the sustainable emerging technologies for treating refractory organic contaminants present in different industrial wastewaters like textile, paper and pulp, pharmaceuticals, petrochemicals, and refineries. This critical review emerges details of advanced oxidation processes (AOPs), mentioning all possible permutations and combinations of components like ozone, UV, the catalyst used in the process. Non-conventional AOP systems, microwave, ultrasound, and plasma pulse assisted are the future of the oxidation process. This review aims to enlighten the role of AOPs for the mineralization of refractory organic contaminants (ROC) to readily biodegradable organics that cannot be either possible by conventional treatment. The integrated AOPs can improve the biodegradability of recalcitrant organic compounds and reduce the toxicity of wastewater, making them suitable for further biological treatment.

Advanced oxidation processes for the removal of mono and polycyclic aromatic hydrocarbons - A review

Aromatic hydrocarbons (AHs) are toxic environmental contaminants presented in most of the environmental matrices. Advanced oxidation processes (AOPs) for the removal of AHs in the account of complete mineralization from various environmental matrices have been reviewed in this paper. An in-depth discussion on various AOPs for mono (BTEX) and polyaromatic hydrocarbons (PAHs) and their derivatives is presented. Most of the AOPs were effective in the removal of AHs from the aquatic environment. A comparative study on the degradation of various AHs revealed that the oxidation of the AHs is strongly dependent on the number of aromatic rings and the functional groups attached to the ring. The formation of halogenated and nitrated derivatives of AHs in the real contaminated water containing chloride, nitrite, and nitrate ions seems to be a challenge in using the AOPs in real systems. The phenolic compounds, quinone, alcohols, and aliphatic acids are the important byproducts formed during the oxidation of AHs, initiated by the attack of reactive oxygen species (ROS) on their electron-rich center. In conclusion, AOPs are the adaptable method for the removal of AHs from different environmental matrices. The persulfate-based AOPs were applied in the soil phase removal as an in situ chemical oxidation of AHs. Moreover, the combination of AOPs will be a conclusive solution to avoid or minimize unexpected or other toxic intermediate products and to obtain rapid oxidation of AHs.

Hierarchical Ultrathin Layered GO-ZnO@CeO2 Nanohybrids for Highly Efficient Methylene Blue Dye Degradation

Highly efficient interfacial contact between components in nanohybrids is a key to achieving great photocatalytic activity in photocatalysts and degradation of organic model pollutants under visible light irradiation. Herein, we report the synthesis of nano-assembly of graphene oxide, zinc oxide and cerium oxide (GO-ZnO@CeO₂) nanohybrids constructed by the hydrothermal method and subsequently annealed at 300 °C for 4 h. The unique graphene oxide sheets, which are anchored with semiconducting materials (ZnO and CeO₂ nanoparticles), act with a significant role in realizing sufficient interfacial contact in the new GO-ZnO@CeO₂ nanohybrids. Consequently, the nano-assembled structure of GO-ZnO@CeO₂ exhibits a greater level (96.66%) of MB dye degradation activity than GO-ZnO nanostructures and CeO₂ nanoparticles on their own. This is due to the thin layers of GO-ZnO@CeO₂ nanohybrids with interfacial contact, suitable band-gap matching and high surface area, preferred for the improvement of photocatalytic performance. Furthermore, this work offers a facile building and cost-effective construction strategy to synthesize the GO-ZnO@CeO₂ nanocatalyst for photocatalytic degradation of organic pollutants with long-term stability and higher efficiency.

da Silva VA, S. da Silva GF, Santos ECS, de S. Baêta E, Brant de Campos J, Carvalho NMF, Malta LFB, Senra JD. Mild and Rapid Light-Driven Suzuki-Miyaura Reactions Catalyzed by AuPd Nanoparticles in Water at Room Temperature

Organic reactions carried out in water under mild conditions are state-of-the-art in terms of environmentally benign chemical processes. In this direction, plasmonic catalysis can aid in accomplishing such tasks. In the present work, cyclodextrin-mediated AuPd bimetallic nanoparticles (NPs) were applied in room-temperature aqueous Suzuki-Miyaura reactions aiming at preparing biaryl products based on fluorene, isatin, benzimidazole and resorcinol, with yields of 77 % up to 95 %. AuPd NPs were revealed to be a physical mixture of Au and Pd particles circa 20 and 2 nm, respectively, through X-ray diffraction, dynamic light scattering, UV-Vis spectroscopy and transmission electron microscopy analyses.

The advanced treatment of textile printing and dyeing wastewater by hydrodynamic cavitation and ozone: Degradation, mechanism, and transformation of dissolved organic matter

The emission standards for textile printing and dyeing wastewater are stricter due to serious environmental issues. A novel technology, hydrodynamic cavitation combined with ozone (HC + O₃), has attracted wide attention in wastewater advanced treatment, whereas the contaminants removal mechanism and transformation of dissolved organic matter (DOM) were rarely reported. This study investigated the removal efficiency and mechanism of HC + O₃. The maximum removal rates of UV₂₅₄, chrominance, COD_Cr, and TOC were 64.99%, 91.90%, 32.30%, and 36.67% in 60 min, respectively, at the inlet pressure of 0.15 MPa and O₃ dosage of 6.25 mmol/L. The synergetic coefficient of HC + O₃ was 2.77. The removal of contaminants was the synergy of ¹O₂, ·OH and ·O₂^-, and high molecular weight and strong aromaticity organic matters were degraded effectively. The main components in DOM were tryptophan-like and tyrosine-like, which were effectively removed after HC + O₃. Meanwhile, most DOM had decreased to low apparent relative molecular weight (LARMW) compounds. Additionally, the HC + O₃ effluent can reach the emission standard in 60 min for 8.07 USD/m³. It can be concluded that HC + O₃ is an effective technology for the advanced treatment of industrial wastewater. This study will provide suggestions for the engineering application of HC + O₃.

Evaluation of degradation performance toward antiviral drug ribavirin using advanced oxidation process and its relations to ecotoxicity evolution

The rapid spread of coronavirus disease 2019 has increased the consumption of some antiviral drugs, wherein these are discharged into wastewater, posing risks to the ecosystem and human health. Therefore, efforts are being made for the development of advanced oxidation processes (AOPs) to remediate water containing these pharmaceuticals. Here, the toxicity evolution of the antiviral drug ribavirin (RBV) was systematically investigated during its degradation via the UV/TiO₂/H₂O₂ advanced oxidation process. Under optimal conditions, RBV was almost completely eliminated within 20 min, although the mineralization rate was inadequate. Zebrafish embryo testing revealed that the ecotoxicity of the treated RBV solutions increased at some stages and decreased as the reaction time increased, which may be attributed to the formation and decomposition of various transformation products (TPs). Liquid chromatography-mass spectrometry analysis along with density functional theory calculations helped identify possible toxicity increase-causing TPs, and quantitative structure activity relationship prediction revealed that most TPs exhibit higher toxicity than the parent compound. The findings of this study suggest that, in addition to the removal rate of organics, the potential ecotoxicity of treated effluents should also be considered when AOPs are applied in wastewater treatment.

Efficient peroxymonosulfate activation of immobilized Fe-N-C catalyst on ceramsite for the continuous flow removal of phenol

Nowadays, developing environmentally friendly catalysts with both low cost and high efficiency was still a challenge in actual organic wastewater purification. Herein, the Fe-N-C catalyst was successfully immobilized on solid waste derived ceramsite for efficient degradation of phenol under continuous flow conditions by activating peroxymonosulfate (PMS). After the introduction of ceramsite, the microstructure of Fe-N-C catalyst was changed from granular structure to worm-like structure, promoting the dispersion of the nanoscale catalyst and providing more reactive sites. Therefore, the phenol removal rate and mineralization rate of the obtained 0.5FNNC within 30 min were up to 96.79% and 71.79%, respectively. In addition, the degradation rate of the optimal composite (0.5FNNC)/PMS system was about 4.06 times higher than that of bare Fe-N-C/PMS system. Intriguingly, the Fe ion leaching from 0.5FNNC during the degradation reaction was significantly lower than bare Fe-N-C owing to the strong catalyst-support chemical bonding. Based on electron paramagnetic resonance, quenching experiments, X-ray photoelectron spectroscopy analysis and electrochemical analysis, it was indicated that the non-radical processes (¹O₂ and high valent iron-oxo species) should be responsible for the phenol degradation. Meanwhile, the possible phenol degradation pathways were proposed, and the intermediates were evaluated for ecotoxicity by ECOSAR. Finally, a preliminary economic analysis of this process was carried out. Overall, this work would provide a new strategy for the construction of ceramsite based multi-pore composite catalysts and the large-scale application of persulfate oxidation technology in organic wastewater treatment.

Novel construction of the catalyst from red mud by the pyrolysis reduction of glucose for the peroxymonosulfate-induced degradation of m-cresol

Red mud of low cost is regarded as a promising alternative to heterogeneous catalysts for activating peroxymonosulfate (PMS) to degrade m-cresol. Improper valence states of metal oxides and coated active substances in red mud greatly hampered its wide application. To solve this problem, the modified red mud (WRMG/700) was prepared by the pyrolysis reduction of glucose in N₂ atmosphere. X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectrum (XPS) analysis confirmed the production of Fe₃O₄, MnO and NiO in red mud and their gathering on the surface of particles. WRMG/700 exhibited the excellent performance toward PMS activation for the m-cresol degradation with 99.02% degradation efficiency and a pH-independent catalytic activity between initial pH 3-8. The removal efficiency of COD increased with the reaction time under the optimized degradation conditions. The free radical scavenging experiments and electron paramagnetic resonance (EPR) test confirmed ¹O₂ played a dominant role during m-cresol degradation in the WRMG/700/PMS system, implying m-cresol degradation was a non-radical oxidation process. Accordingly, the possible reaction mechanism was proposed. WRMG/700 retained its activation performance even after five recycles. This study showed a low cost and simple operation process for m-cresol elimination.

Endocrine disrupting chemicals in the environment: Environmental sources, biological effects, remediation techniques, and perspective

Endocrine disrupting chemicals (EDCs) have been identified as emerging contaminants, which poses a great threat to human health and ecosystem. Pesticides, polycyclic aromatic hydrocarbons, dioxins, brominated flame retardants, steroid hormones and alkylphenols are representative of this type of contaminant, which are closely related to daily life. Unfortunately, many wastewater treatment plants (WWTPs) do not treat EDCs as targets in the normal treatment process, resulting in EDCs entering the environment. Few studies have systematically reviewed the related content of EDCs in terms of occurrence, harm and remediation. For this reason, in this article, the sources and exposure routes of common EDCs are systematically described. The existence of EDCs in the environment is mainly related to human activities (Wastewater discharges and industrial activities). The common hazards of these EDCs are clarified based on available toxicological data. At the same time, the mechanism and effect of some mainstream EDCs remediation technologies (such as adsorption, advanced oxidation, membrane bioreactor, constructed wetland, etc.) are separately mentioned. Moreover, our perspectives are provided for further research of EDCs.

Photo-degradation of sugar processing wastewater by copper doped bismuth oxyiodide: Assessment of treatment performance and kinetic studies

In this study, photo-Fenton-like oxidation method was evaluated for synthetic sugar industry wastewater using visible-light driven Cu-BiOI photocatalyst. Reaction conditions including initial pH, catalyst loading, initial hydrogen peroxide (H₂O₂) concentration, and temperature, were optimized. At these optimized conditions, the total saccharide concentration (TSC) and total organic carbon (TOC) removals were 56.20% and 30.67%, respectively whereas the maximum TSC and TOC removal reached up to 93.35% and 74.72% respectively by decreasing initial sucrose concentration. The kinetic study showed that the reaction order for sucrose and TOC oxidation was determined as 2 for pseudo-homogeneous power law models with respect to sucrose concentration and TOC, respectively.For heterogeneous models, Langmuir-Hinshelwood model based on the mechanism of adsorbed pollutant and oxidant on different catalytic sites was the best fit for oxidation of sucrose and other organic intermediates. According to the catalyst characterization studies, incorporation of copper was successful and Cu-BiOI possesses high photocatalytic activity accomplished by acid-assisted synthesis method.

Enhancing the Photocatalytic Activity of TiO2/Na2Ti6O13 Composites by Gold for the Photodegradation of Phenol

This study aims to synthesize Au/TiO2/Na2Ti6O13 composites to reduce the occurrence of recombination and increase photocatalytic activity in phenol degradation. Gold was used due to its high stability and strong surface plasmon resonance (SPR) properties which make it operate effectively in the visible light spectrum. The prepared composites were characterized using XRD, SEM, TEM, FTIR, and DRS. The results showed that the composite consisted of rutile TiO2 with a crystal size of 38–40 nm and Na2Ti6O13 with a crystal size of 25 nm. The gold in the composite has a crystallite size of 16–19 nm along with the percentage of gold added. Morphological analysis shows that the composite has the form of inhomogeneous spherical particles with gold spread among composites with sizes less than 20 nm. FTIR analysis showed the presence of Na–O and Ti–O–Ti bonds in the composite. The best composite was 3% Au/TiO2/Na2Ti6O13 which had high crystallinity, small particle size, and bandgap energy of 2.59 eV. Furthermore, it had an efficiency 205% better than without gold. After that, cost estimation is proposed as a large-scale application. This study describes the total cost, break-even analysis, and payback analysis for the commercialization needs of the designed photocatalytic catalyst.

Effective removal of organics from Bayer liquor through combined sonolysis and ozonation: Kinetics and mechanism

The presence of organic compounds in the waste liquor is of serious environmental concern that has plagued the development of alumina industry (Bayer Process). The present work attempts to develop a green and efficient process for removal of organics utilizing combined effect of sonolysis and ozonation (US/O₃). The effects of reaction duration, ozone concentration and ultrasonic power are assessed for sonolysis (US), ozonation (O₃) and combination of sonolysis and ozonation (US/O₃). The optimal conditions for US/O₃ treatment system is identified to be a reaction duration of 7 h, ozone concentration of 7.65 g/h, and ultrasonic power of 600 W. The total organic carbon (TOC) removal and decolorization are 60.13% and 87.1%, respectively. The process can be scaled-up to industrial scale, which could potentially serve to be a convenient, safe and sustainable alternative to the exisiting treatment technologies. Additionally, the treated waste water can be reused contributing to an improvement in the overall economics.

Effective degradation of VOCs from wood by Fe2+ chelate activated dual oxidant (H2O2-PS)

Wood is rich in extractives and volatile oils that emit unpleasant odors and some harmful volatile organic compounds (VOCs). Chemical oxidation technologies processes high efficiency on the destruction of aqueous organic components via oxidation by radicals, however, wood block treatment scenarios suffer from the low availability of radicals in aqueous conditions owing to the special structure of the wood blocks, limitations of mass transfer and the short life of free radicals. Herein, ethylenediaminetetraacetic acid (EDTA) is selected as a chelating agent to synthesize EDTA-Fe²⁺ chelate, thus introducing Fe²⁺ into the wood by vacuum impregnation. The Fe²⁺ is evenly distributed and immobilized in the wood to form a chemical oxidation system via in-situ activation of the dual oxidant (H₂O₂-PS), which truncates the contact distance between free radicals and extractives/volatile oils thus enhancing the removal efficiency. Various controlling factors, including EDTA/Fe²⁺ molar ratio, Fe²⁺dosage, PS/H₂O₂ molar ratio, and persulfate (PS) dosage are evaluated. The degradation products of VOCs by headspace solid-phase micro-extraction combined with gas chromatography-mass spectrometry (HS-SPME/GC-MS) indicate that the wood VOC removal rate is ∼80%. The Electron paramagnetic resonance (EPR) analysis further reveals that SO₄^-· and ·OH are the primary reactive species. The characterization of wood properties illustrates that the process has no destructive effect. The results of this work may provide a theoretical basis for feasibility of the practical application of the EDTA-Fe²⁺/H₂O₂-PS system.

Engineering and modeling perspectives on photocatalytic reactors for water treatment

The debate on whether photocatalysis can reach full maturity at commercial level as an effective and economical process for treatment and purification of water and wastewater has recently intensified. Despite a bloom of scientific investigations in the last 30 years, particularly with regards to innovative photocatalytic materials, photocatalysis has so far seen a few industrial applications. Regardless of the points of view, it has been realized that research on reactor design and modeling are now equally urgent to match the extensive research carried out on innovative photocatalytic materials. In reality, the development of photocatalytic reactors has advanced steadily in terms of modeling and reactor design over the last two decades, though this topic has captured a smaller specialized audience. In this critical review, we introduce the latest developments on photocatalytic reactors for water treatment from an engineering perspective. The focus is on the modeling and design of photocatalytic reactors for water treatment at pilot- or at greater scale. Photocatalytic reactors utilizing both natural sunlight and UV irradiation sources are comprehensively discussed. The most promising photoreactor designs and models are examined giving key design guidelines. Other engineering considerations, such as operation, cost analysis, patents, and several industrial applications of photocatalytic reactors for water treatment are also presented. The dissemination of key photocatalytic reactor design principles among the scientific community and the water industry is currently one of the greatest obstacles in translating PWT research into widespread real-world application.

Application of hybrid oxidative processes based on cavitation for the treatment of commercial dye industry effluents

The present work demonstrates the significant role of ultrasound (US) in intensifying the efficacy of the combination with Fenton reagent and/or ozone for the treatment of real dye industry industrial effluent procured from the local industry. Initial part of the work focused on analysing the literature based on combination approaches of US with different oxidants applied for the treatment of real and simulated effluents focusing on the dyes. The work also provides guidelines for the selection of optimal operating parameters for maximizing the intensification of the degradation. The second part of the work presents an experimental study into combined approaches of ultrasound with ozone (O3) and Fenton's reagent for treatment of real effluent. Under optimized conditions (100 W, 20 kHz and duty cycle of 70%), maximum COD reductions of 94.79% and 51% were observed using a combined approach of US + Fenton oxidation followed by lime treatment for the treatment of effluent-I and effluent-II respectively at H2O2 loading of 17.5 g/L, H2O2/Fe2+ ratio of 3, pH of 4, CaO dose of 1 g/L and an overall treatment time of 70 min. US + Fenton + O3 followed by lime was also applied for treatment under ozone loading of 1 g/h for the treatment of effluent-I and it was found that maximum COD reduction of 95.12% was obtained within 30 min of treatment time, indicating use of ozone did not result in significant value addition in terms of COD reduction but resulted in faster treatment. HC (inlet pressure: 4 bar) + Fenton + Lime scheme was successfully replicated on a pilot-scale resulting in maximum COD reduction of 57.65% within 70 min of treatment time. Overall, it has been concluded that the hybrid oxidative processes as US + Fenton followed by lime treatment is established as the best approach ensuring effective COD reduction at the same time obtaining final colourless/reusable effluent.

A Review on the Treatment of Petroleum Refinery Wastewater Using Advanced Oxidation Processes

The petroleum industry is one of the most rapidly developing industries and is projected to grow faster in the coming years. The recent environmental activities and global requirements for cleaner methods are pushing the petroleum refining industries for the use of green techniques and industrial wastewater treatment. Petroleum industry wastewater contains a broad diversity of contaminants such as petroleum hydrocarbons, oil and grease, phenol, ammonia, sulfides, and other organic composites, etc. All of these compounds within discharged water from the petroleum industry exist in an extremely complicated form, which is unsafe for the environment. Conventional treatment systems treating refinery wastewater have shown major drawbacks including low efficiency, high capital and operating cost, and sensitivity to low biodegradability and toxicity. The advanced oxidation process (AOP) method is one of the methods applied for petroleum refinery wastewater treatment. The objective of this work is to review the current application of AOP technologies in the treatment of petroleum industry wastewater. The petroleum wastewater treatment using AOP methods includes Fenton and photo-Fenton, H2O2/UV, photocatalysis, ozonation, and biological processes. This review reports that the treatment efficiencies strongly depend on the chosen AOP type, the physical and chemical properties of target contaminants, and the operating conditions. It is reported that other mechanisms, as well as hydroxyl radical oxidation, might occur throughout the AOP treatment and donate to the decrease in target contaminants. Mainly, the recent advances in the AOP treatment of petroleum wastewater are discussed. Moreover, the review identifies scientific literature on knowledge gaps, and future research ways are provided to assess the effects of these technologies in the treatment of petroleum wastewater.

Hierarchical ultrathin layered MoS2@NiFe2O4 nanohybrids as a bifunctional catalyst for highly efficient oxygen evolution and organic pollutant degradation

Rational design and highly efficient dual-functional catalyst are still difficult to develop for electrocatalytic oxygen evolution reaction and degradation of RhB dye pollutant. Herein, we report a highly efficient "bandgap matching and interfacial coupling" strategy to synthesize nano-assembled ultrathin layered MoS₂@NiFe₂O₄ (MS@NiFeO) bifunctional catalyst constructed by the hydrothermal route and subsequently amine-hydrolysis. The OER performance of the prepared MS@NiFeO catalyst delivers a low overpotential of 290 mV at 10 mA/cm² and Tafel slope is 69.2 mV dec^-1 in an alkaline solution. In addition, the nano-assembled ultrathin layered structure of MS@NiFeO showed a highly efficient (96.37%) RhB dye degradation performance than that of MoS₂ nanosheets and NiFe₂O₄ nanostructures. Unique nanostructure of ultrathin layered MS@NiFeO with suitable band matching, interfacial charge transfer, high surface area and more active sites favored for the enhancement of the catalytic activity. This work presents an unpretentious construction and low-cost production strategy to synthesize bifunctional hybrid catalyst for oxygen evolution reaction as well as degradation of organic pollutant with superior efficiency and longer stability.

Development of microwave assisted-UV digestion using diluted reagents for the determination of total nitrogen in cereals by ion chromatography

The objective of this work is to develop a microwave assisted-ultraviolet (MW-UV) digestion in the presence of dilute HCl and H₂O₂ followed by ion chromatography (IC) measurements for the determination of total nitrogen in cereals. This approach (MW-UV-IC) requires lesser time and does not need environmentally hazardous materials as used in Kjeldhal method. Further, the developed method requires only microliter quantities of dilute HCl and few milliliters of H₂O₂ for the matrix digestion and simultaneous conversion of nitrogen to its ionic species for the subsequent analysis by IC. At the optimized acid concentrations (200 ​μL of 0.1 ​mol ​L^-1 HCl) and microwave power, the nitrogen in the cereals flours is converted to nitrate (NO₃ ^-), nitrite (NO₂ ^-) and ammonium (NH₄ ⁺) ions. The nitrogen species were separated using IonPac AS-20 and IonPac CS-17 columns and then quantified using suppressed conductivity detection. The method was applied to estimate the total nitrogen in flours of various cereals like; wheat (Triticum aestivum), rice (Oryza sativa), finger millet (Eleusine coracana), jowar (Sorghum) and pearl millet (Pennisetum glaucum). The results obtained using proposed method, were in good agreement with that of Kjeldhal method. Further, the precision of the values obtained by developed method was on par with the Kjeldhal method for all the tested flours as verified by F-test (n ​= ​5 and 95% confidence limit). Additionally, greenness assessment tools like analytical Eco-scale and green analytical procedure index (GAPI) suggested the proposed MW-UV-IC method, for the determination of total nitrogen in cereal flours, to be excellently green and safe.